PITCHf/x is a pitch-tracking system, created by Sportvision. Since 2007, every MLB stadium has had the system installed. The system collects information about every pitch, including location and outcome. The pitchRx package in R allows for the easy downloading and mining of PITCHf/x data, along with other useful data. In this talk, I will discuss using PITCHf/x data to analyze umpire performance related to calling balls and strikes. In particular, I will investigate the existence of a home-field bias and the variability of call accuracy across umpires.